Fixes another off-by-one issue when diffing with caching

Refactored commands and blame annotations

src/commands/showBlameHistory.ts

@@ -0,0 +1,26 @@
+'use strict'
+import {commands, Position, Range, TextEditor, TextEditorEdit, Uri} from 'vscode';
+import {EditorCommand} from './commands';
+import {BuiltInCommands, Commands} from '../constants';
+import GitProvider from '../gitProvider';
+
+export default class ShowBlameHistoryCommand extends EditorCommand {
+    constructor(private git: GitProvider) {
+        super(Commands.ShowBlameHistory);
+    }
+
+    execute(editor: TextEditor, edit: TextEditorEdit, uri?: Uri, range?: Range, position?: Position) {
+        if (!(uri instanceof Uri)) {
+            if (!editor.document) return;
+            uri = editor.document.uri;
+
+            // If the command is executed manually -- treat it as a click on the root lens (i.e. show blame for the whole file)
+            range = editor.document.validateRange(new Range(0, 0, 1000000, 1000000));
+            position = editor.document.validateRange(new Range(0, 0, 0, 1000000)).start;
+        }
+
+        return this.git.getBlameLocations(uri.fsPath, range)
+            .catch(ex => console.error('[GitLens.ShowBlameHistoryCommand]', 'getBlameLocations', ex))
+            .then(locations => commands.executeCommand(BuiltInCommands.ShowReferences, uri, position, locations));
+    }
+}